/Engine/Source/Runtime/Experimental/Iris/Core/Public/Iris/ReplicationSystem/Private/FastArrayReplicationFragmentInternal.h
Find the member index of the FastArrayIteArray, used to support FastArrayNetSerializers with extra properties
static uint32 GetFastArrayStructItemArrayMemberIndex ( const [FReplicationStateDescriptor](API\Runtime\IrisCore\Iris\ReplicationState\FReplicationStateDescriptor) * StructDescriptor )